Policy —

One citizen demands: "Do you know why Oakland is spying on me and my wife?"

A low “hit rate”

Specialized LPR cameras mounted in fixed locations or on police cars typically scan passing license plates using optical character recognition technology, checking each plate against a "hot list" of stolen or wanted vehicles. The devices can read up to 60 plates per second and typically record the date, time, and GPS location of any plates—hot or not. (There have been incidents where LPR misreads have led to dangerous confrontations.) Some cities have even mounted such cameras at their city borders, monitoring who comes in and out, including the wealthy city of Piedmont, California, which is totally surrounded by Oakland.

LPR collection began in Oakland back in 2006, and an early OPD analysis showed that the overwhelming majority of the data collected was not a “hit.” In April 2008, the OPD reported to the city council that after using just four LPR units for 16 months, it had read 793,273 plates and had 2,012 hits—a “hit rate” of 0.2 percent. In other words, nearly all of the data collected by an LPR system concerns people not currently under suspicion.

In addition to LPR data, Ars obtained a list of OPD vehicles and found that the most frequently seen one is plate number 1275287, a 2007 Crown Victoria marked patrol car. Between January 15, 2012 and May 31, 2014, the OPD scanned that vehicle 879 times all over town, primarily in the downtown and North Oakland areas. In fact, nearly all of the 100 most frequently seen cars were other OPD vehicles scanned several hundred times each.

Enlarge/ License plate 1275287, a 2007 Crown Victoria marked OPD patrol car, was the most frequently scanned car. It was seen 539 times between January 2011 and May 2014.

Cyrus Farivar

Law enforcement policies vary widely as to how long LPR information can be stored. In California, the wealthy Silicon Valley city of Menlo Park (home to Facebook) retains data for just 30 days. By contrast, the Los Angeles Police Department (LAPD) retains data for two years.

Neither the Oakland City Council nor the OPD has ever imposed a formal data retention limit, though OPD has deleted older LPR data as needed to make room for newer data. As LPR devices and storage prices continue to fall, it's likely the volume and rate of such data collection will continue to rise, and its retention time can become longer.

“If I’m law enforcement, I would keep it forever,” Brian Owsley, a former federal judge turned law professor at Indiana Tech, told Ars. “That’s the privacy advocates’ concern is that this stuff goes into a database—gigabytes are essentially free now—and this stuff stays forever.”

There's no evidence that the OPD has abused its database. But absent any strict controls, auditing, or even basic guidelines, it’s hard to know what might or might not have been done.

“Anyone can get this information”

Further Reading

To make sense of the LPR data—which was originally provided in 18 separate Excel spreadsheet files with hundreds of thousands of lines each—Ars hired Mike Tahani, a Bay Area data visualization specialist. Tahani created a simple tool allowing us to search any given plate and plot the locations on a map.

We did not use the data for any purpose beyond our journalistic attempt to understand what such a large license plate reader dataset reveals. While OPD and other law enforcement agencies have the ability to match a given plate with registration records from the Department of Motor Vehicles and the National Crime Information Center, revealing a car's owner, Ars does not. In cases where we searched a known individual's plates, we did so only with their explicit consent.

Howard Matis, a physicist who works at the Lawrence Berkeley National Laboratory, told Ars that he didn’t know that OPD even had LPRs. With his permission, we ran his plate and showed him a map of the five instances where a camera had captured his car, guessing that they were near where he lived or worked. Matis replied by e-mail: “You are correct, they are places that I and my wife go all the time.”

Matis wasn't worried about OPD capturing such data, but he was less comfortable knowing that the data was released to the media.

“If anyone can get this information, that’s getting into Big Brother,” he told Ars. “If I was trying to look at what my spouse is doing, [I could]. To me, that is something that is kind of scary. Why do they allow people to release this without a law enforcement reason? Searching it or accessing the information should require a warrant.”

Matis immediately fired off an e-mail to Dan Kalb, his city council member:

Dan,

Do you know why Oakland is spying on me and my wife? We haven't done anything too radical or illegal.

I gave my license plate to a journalist and he found my wife's and my car in their database. One of the locations is right near our house.

The astounding thing about this information is that anyone, and I mean anyone, can get this information. Some of the information is more than two years old.

I can see lawyers using this information for lawsuits. I can check where my wife is located. Car companies can see my habits. Insurance companies can check up on their clients. We have entered the world of 1984 with the difference that anyone can get the information.

Ars contacted every member of the Oakland City Council, including newly elected mayor Libby Schaaf, to show them the Oakland LPR data. Dan Kalb, the recipient of Matis' e-mail, was the only council member who agreed to meet. (Neither Mayor Schaaf nor the recently departed mayor, Jean Quan, responded to requests for an interview.) Kalb represents District 1, which includes some of the city’s richer neighborhoods—including Oakland Hills and Rockridge—and other less affluent regions in the city’s northwest.

Enlarge/ Dan Kalb was the only member of the city government who would sit down with Ars to discuss LPRs.

Seated in Kalb's cluttered City Hall office, Ars explained the LPR issue. We asked for Kalb's plate number and, within seconds, showed him what the OPD knew about his travels. Our tool revealed that OPD had seen the councilman 51 times between May 2012 and May 2014.

On 16 occasions, Kalb’s car was scanned parked on the street just outside City Hall in the spaces reserved for council members. On another 20 occasions, at various times of day, Kalb’s car was spotted in a tight group on a certain block in the Temescal neighborhood. When Ars guessed that this block must be where he lives, he said that it was.

“I knew these things existed, but I had not delved into the level of detail that you're sharing with me,” he said.

Kalb is relatively new to City Hall, having only been elected in 2012. Though he did know that the city had LPRs, he said he didn’t know the extent of its usage.

“My awareness is that we have something like this, these mobile LPRs, and I presumed that their primary purpose was to track down stolen vehicles or assist in the investigations of other crimes that knowing the license plate would help,” he told Ars. “It raises the question: what's the purpose of retaining records for a long period of time?”

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Cyrus Farivar
Cyrus is a Senior Tech Policy Reporter at Ars Technica, and is also a radio producer and author. His latest book, Habeas Data, about the legal cases over the last 50 years that have had an outsized impact on surveillance and privacy law in America, is out now from Melville House. He is based in Oakland, California. Emailcyrus.farivar@arstechnica.com//Twitter@cfarivar